Radio compass demonstrator



May 23, M E BLAlN RADIO COMPASS DEMONSTRATOR Filed Aug. 8, 1946 s Sheets-Sheet 2 INVENTOR. lflHEHfiLL E. BL/i/N BY M Zfn/D Yawn M May 23, 1950 M. E. BLAIN RADIO COMPASS DEMONSTRATOR 3 SheetsSheet 5 Filed Aug. 8, 1946 AND W m w m Patented May 23, 1950 T 2.56853 RAfiIJo' eommssnmossrmecit Mer es-u Edward-Blah; Memphis-Irene unification August '3, 1946; see: ha..f68.;1i:i 5 claims.- (01. as -@622) (Grantedunderthan)? March. 3-,-

The invention: deScrl-bedherein may be, Ina/hu fiactured' andiused' by on tor. the Government: for gcvernrmentekl purposes without the payment of: any-royaltythere'on.

I This inventionrelates to atratining or demom strating device and" more'particuliarly to a device for assistinga'xrinstructor in explaining-tow traineethe. use; of a radio compass.

Arr object of the invention is to provide a; dc? vice which will simulate such conditions as may be encountered in actuaihfiight, whereby adjust. ments which may be requireed to; be made flight maybeset up by the student and quickly checked by the instructonto determinethe stu= dents understanding of the-subject, whereby er rors may be detected and: pointed out and" cor recited in minimum time;

Another object of the invention is toprovidew devicewhich will simulate at radio compass; and demonstrate its use by aural as well" asvisuar means:

Further" objects: and: advantages will. be recog ni'zed as theinvention is described in"- detail'; and reference: is had to the drawing, wherein Figi 11 is. a; perspective view of my radio com-- pass demonstrator:

Fig. 2' is aw schematic vertical axial see-hon through thedev-icet V Fig: 31 is a; schematic-top plan view'of the tie vice.-

Iiike reference characters refer to like parts thrcughoutthe several views; J

The: base I and housing; 1'2 constitute? the framework of the device;- The uppe'i' sideof the: housing isprovided with awbearing hub l -4.within which averti'calshaft IB' is rotatable: The bearing hub: Ithas-a; reduced upper end. I8-upon whichra; visual:representation-ofa magnetic compass cardZB is rotatable;

The-vertical shaftlfi exter'i'ds above the. hub: partl8 and a miniature airplane 2*2 is mounted thereon; There. is enough friction between-' theairplane and: the shed tto" cause them to turn tee gether when: one isrotated. A1 pointer. 2:4 has one: end fastf to;- the": bottom of the.-:plane: 22 and the other ends. pointing. to: the graduaitioh'sonathe compass card: The -nointer. 24 r corresponds to the? lubo'er' line= on" the magnetic" eomfiass. case which also' tliHl'S' with the; plane; The b'ase HF is-lbrou'ght to a' p 'int' as; at -23 and hasa: line 25 1 which; in operation; pj'ointe'zd to I an: imaginary radio:- station :21 from. which: the: simulated signallislassumedtol-b.e':coming:- The pointer 'uainiaiy be. refer-red to 'zis th'e basestation pointer am'd the line: 2.5. asthe base station pointer line;

amendedApril-;.1928; 370 o. G. 157) Fixed tothetop of; the airplane 22 and concentrio. with the shaft. l6 a'pilots bearing indicator in; the form.- ofan azimuth scale 26 graduated to 360 with 0 and 180 fore and. aft, respectively. on the axis of the plane. A.pointer 28 extendsfrom the upper end. of the shaft I6, the free end of the pointer being; adapted to register with the graduationson the azimuth scale-26. The pointer 28 may be referred to. as the pilots bearing indicator needle.

) Airing 30 made in representation of a; loop antenne is. fast on the upper end of the shaft l6. for. coincident rotation therewith. The plane of the loop 30 is at right angles to. the plane of the bearingindicator needle 28. H

Mounted within the housing I2 on the lower end of the, shaft [6 to rotatein unison therewith is a. disc 32 which-carries the collector ring 34 which is. insulated from the disc by-the ring of in! sulati'bnst. A power outletjack 35 has its. outer contact 38' grounded to the housing and its cen, ter contact 40 hearing on, a; spring 42 which holds 3:. brush 44. against the. collector ring 34. The intier Contact 40" andldrush 44 are separated from the outer contact 38" alnd'hdusing l2 by anin sula ti'ng bushing 39.- The two contacts 38-4001 the jack 35 may be electrically connected to head fihohe's" 33 o'rother electro-acoustical transducer in usual manner. A pair of secondary coils 46" within a casing 487 are connected, one end to the) n5? 34 25nd the other end to ground. The or in which the coilslfiarejmounwd causes t em toswing aboutjthe axis crane shaft l6 when the: 150 530 is turned. v t Mounted withintliehouslng" IZ on the base 10 is acasing 50 contain'in ga' pair of connected pritheir? can: 52 supported on insulators 53, the ends of the coils being connected tov the: terminals 54 and 5B of a power inlet jack 5B. When the loop 30 isturned so that the plane of the loop coincides wit i the 1ine25on the base H), the axes of the QGil..: 4 5 ai -1d 52 will coincide in Fig 2, and maxlinu'ni' i niductainlce will be ha d. Minimum in ducts; or 111111 will" beiefiect'ed when the plane or the- 501: so'i-s norma'rtothe bais's tttion pointer he operation or thefdievice is s renown u fllhe po'werj inlet j'alt 5'3 maybe plugged into Bi ole ect' so'that' tlieline winter I df toward: an':imagiri'aryraldio stetion' sewn; Fi Ihfrom 'Which the simulated signeil isassuihe'd tube coming It the device isbeing: placed one the coils 52 at which point the minimum or null signal will be heard on the head set which is connected to the jack 35. This signal will be heard whenever the loop pointer 28 points to the station with which the line 25 is aligned regardless of the heading of the aircraft. In the drawing, Fig.

tion is 330 degrees and the heading is 15 degrees.

Having described my invention,-I claim:

3, the radio compass bearing selected for illustrafor simulating a loop antenna fast on the upper end of said shaft, a collector ring insulatedly carried on an enlarged portion at the lower end of said shaft, a phone-jack having its inner terminal electrically connected to said collector ring and its outer terminal grounded on said housing, a primary Winding insulatedly carried on said base with axis fixed with respect to the station pointer line, means electrically connecting the ends of said primary winding to a signal source, a secondary winding carried on said enlarged portion with one end grounded on said enlarged portion and the other end electrically connected to said collector ring, said secondary winding having an axis in the same plane as that of the primary winding when the plane of the loop coincides with the plane of the base station pointer line,

a'headset, and means electrically connecting the l. A device for teaching the use of a radio compass. which consists of a base, a pointer line on said base adapted to be pointed toward an imaginary radio station, a housing on said base, a hub on the top of said housing having a reduced portion at its upper end, a vertical shaft rotatable in said hub and extending upwardly therethrough and downwardly into said housing, a simulation of a magnetic compass card rotatable on said reduced portion, a miniature airplane frictionally mounted on the upwardly extending and of said shaft, a pointer fixed on the bottom of said airplane for registering with the indicia on card, an azimuth scale fixed on the upper side of said airplane, a bearing indicator needle having one end fixed to said shaft and the free end adapted to register with the graduations of said azimuth scale, a ring for simulating a loop antenna fast on the upper end of said shaft, a disc on the lower end of said shaft, a collector ring insulatedly fixed on said disc, 2 brush insulatedly carried on said housing and having con-' tact with said collector ring, a phone-jack havin its inner terminal in electrical contact with said brush and its outer terminal grounded on said housing, a pair of connected primary coils insulatedly carried on said base within said housing having their axes spaced apart but parallel to the shaft axis and in the plane of the base station pointer line, means electrically connecting the ends of said primary coils to a signal source, a pair of connected secondary coils carried on said disc with one end grounded on said disc and the other end electrically connected to collector ring, said secondary coils being coaxial with said primary coils when the plane of the. loop coincides with the plane of the base station pointer line, a headset. and means electrically connecting the terminal of said phonejack to said headset.

p 2. A device for teaching the use of a radio compass, which consists of a base, a pointer line on said base adapted to be pointed toward an imaginary radio station, a housing on said base, a vertical. shaft rota-tably supported in said housing and extending from within said housing upwardly therethrough, a simulation of a magnetic compass card rotatable about the axis of said shaft above said housing, a miniature airplane frictionally mounted on the upwardly extending end of said shaft, a pointerfixed on the bottom of said airplane for registry with the indicia on said card, an azimuth scale fixed on said airplane,

a bearing indicator needle having one end fixed to said shaft and the free end adapted to register with the graduation of said azimuth scale, a ring terminal of said phone-jack to said headset.

3. A device for teaching the use of a radio compass, which consists of a framework, a line on said framework adapted to be pointed toward an imaginary radio station, a shaft bearing in said framework, a vertical shaft rotatably supported in said shaft bearing and extending upwardly and downwardly from said bearing, a simulation of a rotatable magnetic compass card coaxed with said shaft, a miniature airplane frictionally mounted on the upwardly extending end of said shaft, a pointer fixed on the bottom of said airplane for registry with the indicia on said card, an azimuth scale fixed on said airplane, a bearing indicator needle having one end fixed to said shaft and the free end adapted to register with the graduation of said azimuth scale, a ring for simulating a loop antenna fast on the upper end of said shaft, a collector ring insulatedly carried on said shaft below said shaft hearing, a phone-jack having one terminal in electrical communication with said ring and the other terminal grounded on said framework, a primary inductance insulatedly affixed to said framework, means electrically connecting the ends of said primary inductance to a signal source, a secondary inductance supported for coincident rotation with said shaft with one end in electrical communication with said framework and the other end electrically connected to said collector ring, said secondary inductance having anaxis in the same plane as an axis of the primary inductance when the plane of the loop coincides with the plane of the framework line, a headset, and means electrically connecting the terminal of said phone-jack to said headset.

4.A device for teaching the use of a radio compass, which consists of a framework, a line on said framework adapted to be pointed toward an imaginary radio station, a vertical shaft rotatably supported by said framework, a miniature airplane frictionally mounted on an upwardly extending end of said shaft, an azimuth scale fixed-on said airplane, a bearing indicator needle having one end fixed to said shaft and the free end adapted to register with the graduations of said azimuth scale, a ring for simulating a loop antenna fast on said shaft, a primary inductance insulatedly carried on said framework, means electrically connecting said primary inductance to a signal source, a secondary inductance supported on said shaft to rotate therewith, said primary and secondary inductances being so positioned with respect to each other that maximum inductance is had when the plane of the loop coincides with the plane of the base station pointer line, a headset, and means electrically 5 connecting the terminal of said secondary inductance to said headset.

5. In a device for teaching the use of a radio compass, a framework, a line on said framework adapted to be pointed toward an imaginary radio base station, a shaft rotataloly supported by said framework, a ring for simulating a loop antenna and a disc both fast on said shaft to rotate there-- with, a secondary winding comprising a pair of secondary coils carried on said disc, said coils having their several axes one hundred eighty degrees apart, parallel with, and equidistant from the shaft axis and in the plane of the loop, a primary winding compressing a pair of primary coils insulatedly and nonrotatably supported on the framework also having their several axes one hundred eighty degrees apart, parallel with, and

equidistant from the shaft axis and in the plane of the base station pointer line, conducting means adapted for connecting the ends of said primary winding to an electric current source, a collector ring insulatedly supported on said disc, one end of said secondary winding being grounded to said REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,321,799 Cone, Jr., et al. June 15, 1943 2,326,764 Crane Aug. 17, 1943 2,333,933 Horr Nov. 9, 1943 2,346,693 Lyman Apr. 18, 1944 2,366,603 Dehmel Jan. 2, 1945 2,402,271 Andrews M June 18, 1946 2,404,386 Levine July 23, 1946 2,418,834 Hartman Apr. 15, 1947 2,450,240 Kail Sept. 28, 1948 

